The function of a dehydrogenation process, when utilized in hydrocarbon processing, is to convert paraffinic hydrocarbons to their corresponding olefins.
Thus, propane is converted to propylene: EQU C.sub.3 H.sub.8 =C.sub.3 H.sub.6 +H.sub.2
or isobutane is converted to isobutylene: EQU iC.sub.4 =iC.sub.4 H.sub.8 +H.sub.2
These are two examples of the use of the process.
The reactor effluent stream from such dehydrogenation processes contains these components in the vapor phase. A cryogenic process is employed to condense the C.sub.3 or C.sub.4 components as a liquid phase product. The residual vapor stream is required free of the C.sub.3 or C.sub.4 components to minimize their losses.
A method and apparatus for the separation of C.sub.4 hydrocarbons from a gaseous mixture containing the same are described in U.S. Pat. Nos. 5,414,188, issued May 9, 1995, and 5,505,048, issued Apr. 9, 1996, hereby incorporated by reference.
These patents are directed to the separation of the C.sub.4 hydrocarbons in a series of cooling for condensation, phase separation, and expansion process steps with refrigeration by indirect heat exchange between expansion products to save energy and power consumption.
It is desirable to provide a new and improved cryogenic separation process and apparatus system for the
It is desirable to provide a new and improved cryogenic separation process and apparatus system for the separation of C.sub.3 or C.sub.4 gaseous mixtures with hydrogen, such as produced in dehydrogenation processes to permit the use of lower Cost and more economical materials of construction in the process, to increase the extraction of energy in the process, to reduce the size of heat exchangers employed in the process and apparatus, and to otherwise improve the efficiency and economy of the separation process and apparatus system.